I use my Lowr.Paper graph on Lake Mich.and any of our spring fed lakes in WI.If you don't follow the thermocline you're straining a lot of fishless water.The spring fed lakes are pretty cold all year round and with the thermo on the graph you can fish in or above it.

2500,,,the magic number in power down to 1800 feet.Even though technology has taken over as digital I can still play with the knobs,,,that is the sensitivity,,,,,I mean depyh finder .My old Vexilar555 did the same but not as precisely.I think that "Grey Line" found its meaning with the paper graph that way.It does have a down side,,,paper is worth a lot of money.